Done properly, room treatments can work miracles. And no, I'm not selling or making them. And you don't have to spend a fortune. I sprang for RPG ProFoam from Audio Advisor when they sold six 24" squares for fifty bucks. That was the best value in "over-the- counter" room absorption I could find. But if you want to save a lot of moolah, you might try looking in the crafts department at your local wally-world. I found 22" square by 4' thick polyfill for just a few bucks. It's white, but I assume it could be dyed or covered with something and still be effective.
In my experience, killing early reflections is the most helpful. You can use a mirror and a flashlight, with the help of an understanding loved one, to find the right spots. Just don't overdo it. Too much absorption will suck the life right out of the music - nobody would want to listen to music in an anechoic chamber. But when you get it dialed in, it can improve imaging and clarity tremendously.
It can't be over-emphasized - the listening room is probably the most important component in determining your overall sound quality.
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JDMcCall